Osteoporosis, the leading bone disease in the world, is a disease in which the quality of the bone weakens – leading to an increased risk of fractures (broken bones). It is a silent disease which is largely treatable and even preventable in the majority of people. However, without prevention or treatment, osteoporosis can progress causing pain, disability and loss of independence. The most common bones to break are the wrist, hip and spine, however it can affect any bone.
Osteoporosis can affect both men and women and, although quite rare, can even affect children. In South Africa the incidence of osteoporosis in the white, Asian (from the Indian sub-continent) and mixed-race populations appears to be similar to that of developed countries although no fracture data exist. Osteoporosis at the hip is less prevalent in the black populations, although vertebral bone mass, and possibly also vertebral fracture prevalence, in black and white South Africans appear to be similar. The present population in South Africa is estimated to be 50 million, of this 16% (8 million) is aged 50 or over and 3% (1.6 million) is 70 or over. By 2050, it is estimated that 28 % (13.6 million) of the population will be 50 or over and 8 % (4 million) will be 70 or over, while the total population will stay around 50 million.
Our bone health and strength is determined to a large extent by factors outside of our control such as genetics, gender and age. However, there are factors that we can control such as our diet and physical activity and these are particularly important during adolescence, when bones are still developing. A balanced diet which provides ‘bone-friendly’ nutrients such as calcium, phosphorus, protein, vitamin D, zinc and magnesium is essential. Dairy foods are rich in a number of these nutrients. Regular participation in ‘weight-bearing’ activities (any activities that put the full weight of our body on our feet and legs) is also needed. Examples include: brisk walking, running/jogging, tennis and most team sports. Other bone-friendly advice includes maintaining a healthy body weight, avoiding excessive alcohol intake and not smoking.
In addition to calcium, vitamin D and phosphate, adequate intake of dietary protein is recommended for the promotion of bone health and the prevention of osteoporosis. This must start in childhood and continue throughout life. Owing to the interaction between calcium and protein, both should be consumed in adequate amounts to optimise the beneficial dietary effects on bone health. Dairy products – especially milk – have optimal nutrient proportions for bone health, particularly with regard to the high calcium– protein ratio. Without dairy intake, it is difficult to meet calcium requirements and some of the beneficial effects of this mineral appear to be dairy specific. Individuals and nations should strive to increase the consumption of dairy as it has a health-economic impact: millions in health care costs related to hip fractures can be saved annually if dairy intake is increased.
There is a theory that the protein and phosphate in dairy products make them ‘acid-producing’. Acid production could cause minerals to be leeched from the bones in order to neutralise the acid, which would in turn compromise bone health. However, the science does not support this theory and, in fact, it is established that protein and phosphorus are essential nutrients for bone health. However, scientific evidence does not support any of these claims. Milk and dairy products neither produce acid upon metabolism nor cause metabolic acidosis, and systemic pH is not influenced by diet. Additionally, the role of calcium in building and maintaining bones is well-recognised and dairy foods such as milk, yogurt and cheese are among the best dietary sources of calcium.